Subaru Legacy IV (2008 year). Manual - part 358

EN(H4DOTC)(diag)-253

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CM:DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT HIGH (MT MODEL)

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-165, DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT
HIGH (MT MODEL), Diagnostic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
Improper idling

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-07063

ECM

31

B128

B128

T9

1

B55

B136

B122

11

TCM

B55

6

1
3 4

2

T12

NEUTRAL
POSITION

SWITCH

1 2 3 4
5 6 7 8

B122

: AT MODEL

*

*

*

3

T12

1

2

AT

: MT MODEL

MT

B136

5

6

7 8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16

17 18 19 20 21

33 34

29

32

30

31

35

1 2

MT

AT

MT

5

6

7

2

1

3

4

29

10 11 12 13 14 15

25

24

16

30

9

8

17 18 19

20
28

21 22 23

32

31

26 27

33

34 35

T2

: TERMINAL No. OPTIONAL 
 ARRANGEMENT

EN(H4DOTC)(diag)-254

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever in neutral.
3) Measure the voltage between ECM and 
chassis ground.

Connector & terminal

(B136) No. 31 (+) — Chassis ground (–):

Is the voltage less than 1 V?

Repair the poor 
contact of ECM 
connector.

Go to step 2.

2

CHECK HARNESS BETWEEN ECM AND 
NEUTRAL POSITION SWITCH CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
transmission harness connector (T9).
3) Measure the resistance of harness between 
ECM and transmission harness connector.

Connector & terminal

(B136) No. 31 — (B128) No. 1:

Is the resistance less than 1 

:? Go to step 3.

Repair the open 
circuit in harness 
between ECM and 
transmission har-
ness connector.

3

CHECK HARNESS BETWEEN ECM AND 
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance of harness between 
ECM and transmission harness connector.

Connector & terminal

(B128) No. 3 — (B136) No. 6:

Is the resistance less than 5 

:? Go to step 4.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and trans-
mission harness
connector
• Poor contact of
coupling connector

4

CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever in neutral.
2) Measure the resistance between transmis-
sion harness connector terminals.

Connector & terminal

(T9) No. 1 — No. 3:

Is the resistance less than 1 

:? Repair the poor 

contact of trans-
mission harness 
connector.

Repair the open 
circuit of transmis-
sion harness or 
replace the neutral 
position switch. 
<Ref. to 5MT-35, 
Switches and Har-
ness.> <Ref. to 
6MT-41, Neutral 
Position Switch.>

EN(H4DOTC)(diag)-255

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CN:DTC P1152 O2 SENSOR CIRCUIT RANGE/PERFORMANCE (LOW) (BANK1 

SENSOR1)

DTC DETECTING CONDITION:
• Two consecutive driving cycles with fault
• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-166, DTC P1152 O2 SENSOR CIRCUIT RANGE/
PERFORMANCE (LOW) (BANK1 SENSOR1), Diagnostic Trouble Code (DTC) Detecting Criteria.>

CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-
52, OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PRO-
CEDURE, Inspection Mode.>.
WIRING DIAGRAM:

EN-05669

SBF-5

B47

B21

E2

B21

E2

1

2

4

6

3

5

E

E

C2

C3

B8

B9

B1

B134

4

3

2

1

E79

3 4

1 2

3

4

1

2

5

6

B21

B47

E79

B134

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17

18 19 20 21

33 34

29

32

30 31

A:

B135

B:

B136

C:

B137

D:

1 2 3 4

12 13 14 15

5 6 7 8

16 17 18 19

9 10 11

20 21 22

23 24 25 26 27 28 29 30 31 32 33

35

34

37

36

39

38

41

40

43

42

44

45

47

46

49

48

51

50

53

52

54

A:

D2

A5

D3

E2

B21

E

35

34

40

D7

36

D1

37

B138

*

*

*

16

10 11 12 13 14 15

25

24

30

9

8

7

17 18 19 20
28

21 22 23

29

32

31

1

2

3

4

5

6

27

26

33 34 35

B136

C:

B135

5

6

7

8

2

1

9

4

3

10

24

22 23

25

11 12 13 14 15

26 27

28

16 17 18 19

20 21

29 30 31

32 33

34 35

B137

5

6

7

8

2

1

9

4

3

10

22 23

11 12 13 14 15

24 25

26

16 17

18 19 20 21

27

28 29

30 31

B:

D:

1 2 3 4
5 6 7 8

B138

42

26

43

15

MAIN RELAY

BATTERY

FRONT 
OXYGEN (A/F)  
SENSOR

ECM

: TERMINAL No. OPTIONAL 
  ARRANGEMENT 
  AMONG 1, 2, 5  AND 6

EN(H4DOTC)(diag)-256

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK FRONT OXYGEN (A/F) SENSOR 
CONNECTOR AND COUPLING CONNEC-
TOR.

Has water entered the connec-
tor?

Completely 
remove any water 
inside.

Go to step 2.

2

CHECK HARNESS BETWEEN ECM AND 
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and 
front oxygen (A/F) sensor.
3) Measure the resistance of harness between 
ECM and front oxygen (A/F) sensor connector.

Connector & terminal

(B135) No. 9 — (E79) No. 1:
(B135) No. 8 — (E79) No. 3:

Is the resistance less than 1 

:? Go to step 3.

Repair the harness 
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and front oxy-
gen (A/F) sensor
connector
• Poor contact of
coupling connector

3

CHECK POOR CONTACT.
Check for poor contact in the front oxygen (A/F) 
sensor connector.

Is there poor contact in front 
oxygen (A/F) sensor connec-
tor?

Repair the poor 
contact of the front 
oxygen (A/F) sen-
sor connector.

Replace the front 
oxygen (A/F) sen-
sor. <Ref. to 
FU(H4DOTC)-46, 
Front Oxygen (A/F) 
Sensor.>